Jack, Jane and Roger prepare for an Earth Day test to see who can spend an entire without harming the environment. Roger receives a letter from an old girlfriend, and decides he wants to return home to be with her. Cheetah and Tantor act as judges for the contest. Roger, who is set on leaving, decides to journey on his mountain bike, but ends up having to be saved by Tarzan. An encounter with a rhino makes Roger change his mind about leaving, when all learn a lesson about saving the planet.